Well, with the latest episode, I can tell you one thing, snipers have done their homework in the art of killing someone. You see, the myth here is that, given enough time, you can dodge a bullet. While this is true in theory, the myth is sadly BUSTED!
There is indeed a point to react fast enough, but the distance required means you'd NEVER see it coming. You wouldn't be able to react in time because of that.
So yeah, you can't dodge a bullet, even from a sniper.